Incandescent electric lamp for projection apparatus



Sept. 29, 1931. J. MARETTE INCANDESCENT ELECTRIC LAMP FOR PROJECTION APPARATUS Filed May 17, 1928 2 Sheets-Sheet 1 ags lNvtZNTooa, WWW-J Sept. 29, 1931. J. MARETTE 4 1,325,078

INCANDESCENT ELECTRIC LAMP FOR PROJECTION APPARATUS Filed May 17, 1928 2 Sheets-Sheet 2 J qj es MGYC++QI INVEN'TORJ iii-1:132: 450

Patented Sept. 29, 1931 UNITED STATES,

PATENT OFFICE JACQUES MARETTE, or PARIS, FRANCE, ASSIGNOR T0 PATIEIE CINEMA ANCIENS nrABLIssEmENTs PATHE FRERES, or PARIS FRANCE INCANDESCENT ELECTRIC LAMP FOR PROJECTION APPARATUS Application filed May 17, 1928, Serial No. 278,592, and in France June 1, 1927.

The present invention relates to an incandescent lamp for projection apparatus permitting the obtainment of the exact vertical position as well as the angular position of the lamp filament with reference to the opticalv system of the apparatus employingthe said lamp.

It has already been proposed for this purpose to dispose upon the lamp base a ring provided with a tenon cooperating with the lamp socket and with a slot or recess formed in the said socket.

According to the present invention, three or more tenons are placed in an unsymmetrical position upon the peripheryof a ring mounted on the lamp base, and are engaged in three or more corresponding slots or recesses formed in the lamp socket or in a ring secured thereto. Each of the said tenons carries a stud which is well adjusted and is placed in contact with a suitable stop disposed in theslot corresponding to the tenon.

The said device can be used for lamps having the lamp base at the top as well as for lamps having their lamp base at the bottom.

Further characteristics of the invention will be specified in the following description.

The appended drawings show by way of example three embodiments of the invention.

Fig. l. is a vertical section of the lamp socket and of its removed cover shown in an elevational view and relating to the first embodiment.

Fig. 2 is a cross section of the lamp socket and cover, which latter is placed on the socket.

Fig. 3 is a plan view of the socket without the cover.

Fig. 4 is a partial section of a lamp socket with its lamp, according to a second embodiment.

Fig. 5 is a perspective view of the ring provided with pairs of slots;

Fig. 6 is the corresponding plan view of said ring.

Fig. 7 is a sectional view of the same socket, with its cover in position.

Fig. 8 is a sectional view of a lamp socket according to a thirdembodiment of the invention.

In the example shown in Figs. 1 to 3, the base or cap 1 of the lamp bulb 2 has mounted thereon the ring 3 which carries on its external periphery three unsymmetrical tenons 4 which are preferably formed in one with the ring; said tenons are engaged in the slots 5 formed in the lamp socket 6, and the said slots will obviously have an unsymmetrical position with reference to the lamp socket corresponding to the position of the tenons 4 on the ring 3.

In this manner, when the tenons 4 are inserted into the slots 5, the lamp bulb can assume only one position in virtue of the unsymmetrical position of the said tenons and slots. The tenons 4 are provided on one face with the bosses 7 which preferably consist of a drop of a soldering material and are adapted to make contact with a suitable surface 8 provided at the end of each slot 5. The surface portion 8 preferably consists of a brass ring forming a shoulder which is imbedded in the insulating substance of the lamp socket when moulded. The height of the bosses 7 is exactly determined, when the lamp is standardized, so that when the said bosses make contact with the surface 8, the proper height of the lamp filament will be accurately determined by the contact between said bosses and shoulder.

A cover 9, which is lined with a metallic member or shell 10 which is externally threaded, may be screwed into a tapped conducting ring 11 which is disposed at the upper end of the socket 6. A spring 12 is secured to the upper part of the inside of the cover and presses upon the central terminal piece "13 of the lamp, thus applying the bosses 7 upon their contact member 8, as shown in Fig. 2. Two conducting bars 14 are imbedded in the insulation of the socket and are connected respectivel with the contact member 8 and the con ucting ring 11, thus assuring the electrical connections for the lamp. The terminal of the .lamp bulb which ends at the lamp base is connected with one of the conductors 14 by means of the ring 3, the tenons 4, the

bosses 7 and the contact member 8; the other terminal of the lamp bulb which is connected with the upper plate 13 of the lamp base is connected with the other conductor 14 by means of the spring 12, the shell 10 and the ring 11.

When the lamp is in position, it is firmly held by the spring 12 which presses the three bosses 7 upon the contact member 8 situated at the ends of the slots 5 whereby the filament will occupy the proper position in the vertical direction, while at the same time the filament has the proper angular position due to the coincidence between the tenons 4 and slots 5.

The construction shown in Figs. 4 to 7, instead of being employed with a lamp Whose base is placed at the top, is adapted for use with lamps whose base is situated at the bottom. If the device of Figs. 1 to 3 were used with such latter lamps, it would be necessary to hold the lamp in the notches until the socket cover is entirely screwed in, whence there would be some risk of breaking the lamp and of producing bad contacts. To obviate such defects, the base 1 of the lamp bulb 2 is provided as in the preceding case with a ring 3 carrying three unsymmetrical tenons 4. The lamp socket 15 is provided with a metallic ring 16 making contact with a shoulder 17 formed on the said socket; said ring 16 carries three pairs of slots or notches placed in the unsymmetrical position in the same manner as the tenons of the ring. Each pair of slots comprises a slot 18 extending entirely, through the socket, and a slot 19 extending only partly through the said socket, in the vertical direction. The two slots 18 and 19 are connected together by a transverse channel 20. To place the lamp in position, the tenons 4 are inserted clear to the ends of the slots '18, and the lamp is then given a fraction of a turn in such manner that the tenons will pass along the channel 20 and reach the bottom of the slots 19. At this time, the spring 12, which is disposed in the cover 9 and bears upon the central contact piece 13 of the lamp, presses the bosses 7 carried by the tenons 4 upon the upper face of the slots 19. 'In this position, the tenons 4 engaged in the slots 19 will assure the proper angular position of the filament and the bosses 7 which are pressed against the upper face of the slots 19, will thus assure the exact vertical position of the lamp. As in the preceding case, the cover 9 is screwed by means of a threaded metallic'shell 10, to a conducting ring 11 disposed in a recessof the socket 15.

The conductors 14, which are imbedded in the insulation of the socket, respectively connect the conducting ring 11 and the ring 16 with the source of current. The electric circuit is thus closed as in the preceding case.

It is thus observed that in this construction, the stable position of the lamp is assured by three points of contact 7 in the vertical direction, and by the slots 19 in the angular direction. This arrangement can be used not only in the case in which the lamp socket is in the bottom position, but can be employed for all positions of the lamp.

The device shown in Fig. 8 relates to a vertical disposition of the lamp with the lamp base at the bottom. As before, the base or cap 1 of the lamp 2 is provided with a ring 3, carrying three unsymmetrically disposed tenons 4 provided with bosses 7. The said tenons engage the slots 21 of a metallic ring 22 in contact with a shoulder 23 on the socket 24. When the lamp is inserted into the socket, the bosses 7 make contact with the shoulder 25 formed in the ring 22 and constituting a bottom for the slots 21. A rod 26 makin contact with the central terminal plate 13 of the lamp, due to the action of the spring 27, is terminated by the nuts 28 connected with one pole of the source of current. The other pole is connected, through the insulation, with the ring 22. The spring 27 would tend to raise the lamp and to separate the bosses 7 from the shoulder 25.- In order to properly apply the bosses 7 against the shoulder 25, a washer 30, provided with three unsymmetrically disposed push-pieces 31 adapted to engage in the slots 2, is pushed towards the ring 3 by the cover 29 when the said cover is screwed upon the socket 24.

With this device, the stable position of the lamp will be assured due to the three contact points 7 bearing upon the shoulder 25. These contact points 7 and the contact surfaces 25 provide for the proper vertical position of the lamp, whilst the engagement of the tenons 4 in the slots 21 assures the proper angular position of the filament.

Obviously, instead of employing three unsymmetrical ,tenons engaged in three slots, the device may comprise a greater number of tenons and the corresponding number of s ots.

The constructional forms herein represented are obviously susceptible of numerous modifications without departing from the spirit of the invention.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

In a lighting device for rojection apparatus, the combination oi. an ordinary glow lamp having a metallic cap and a cen tral contact piece for leading the current to the filament, a metallic ring secured to the cap of said lamp, a number of projections unsymmetrically disposed on said ring,

a socket of insulating material adapted to receive said lamp cap and provided with slots in equal number and disposed in the same unsymmetrical relation as said projections and adapted to engage said projections, an annular metallic stop member secured in said socket at the inner ends of said slots and on which said projections are adapted to bear, an annular metallic fitting on said socket, a cover for said socket provided with an inner metallic sleeve adapted to engage said fitting, metallic means connected with said sleeve for pressing against said central contact piece of said lamp, whereby said projections are applied on said annular stop member and means for leading current to said metallic stop member and to said metallic fitting.

In testimony whereof I have signed my name to this specification. a

JACQUES MARETTE. 

